Various types of relief valves are known in the art, including those controlled by springs, magnets, and other biasing mechanisms. The prior art that relied on magnets, however, are deficient. The magnets in these valves were exposed to the flow of fluids. This exposure to the fluid risks decreasing the performance of the valve as any magnetic solids or contaminants adhere to the magnets. Thus, the prior art valves in which the magnets were exposed to fluid flow typically required stringent limits on the types of fluids and any contaminants or solids within the fluids that may be used with those valves. In addition, prior art valves typically required frequent preventive maintenance to minimize any degradation in performance.
Thus, there is a need for a low-cost magnetically controlled actuation device, such as a relief valve, in which the magnets are not exposed to the fluid flow. In addition, there is a need for a magnetically controlled actuation device in which a set force of the device is a linear function, an exponential function, or a combination of a linear function and an exponential function.